Funding is a subsidy only if it comes from tax/borrowing sources that aren't related to the thing being subsidized. If taxes levied on driving fund driving, that's not a subsidy. Also that page seems to be talking about all transport including railways, but we're only interested in roads here.

Germany spends ~16B EUR per year on roads at the federal level:

https://www.statista.com/statistics/1293915/federal-expendit...

The amount it gets from motor taxes is vastly in excess of that:

https://www.destatis.de/EN/Themes/Society-Environment/Enviro...

That's not surprising because Germany has the highest motor taxes in Europe:

https://www.acea.auto/press-release/motor-vehicle-taxation-b...

The US does subsidize roads but it doesn't have to, hasn't done so in the recent past and arguably shouldn't be doing so.

Germany is highly federal. The federal government only covers a portion of the cost of road construction and maintenance, with state and local governments carrying much (a majority, I think) of costs.

From what I see in your 2nd link, motor taxes do not even cover the federal government's contribution to road construction and maintenance, not to even mention what state and local governments pay.

You're saying the US doesn't have to subsidize roads, but removing that subsidy would require the US to raise fuel taxes and tolls by 200%. Rail can also break even if prices are increased. The reason governments subsidize HSR is because it has positive externalities.